1. Field of the Invention
The present invention relates to a mass spectrometer, and more particularly to processing of mass spectrum data.
2. Description of the Related Art
As a method for identifying components of an unknown mixed sample, it has been widely practiced to connect any separation unit, e.g., a chromatograph, to a mass spectrometer, and to analyze a resulting mass spectrum by searching a database in which mass spectra of known compounds are stored beforehand. Methods of searching a mass spectrum database are disclosed in JP,A 11-64285 (Patent Reference 1), JP,A 2001-50945 (Patent Reference 2), JP,A 8-124519 (Patent Reference 3), JP,A 2001-249114 (Patent Reference 4), U.S. Pat. No. 6,624,408 (Patent Reference 5), etc.
A liquid chromatograph (LC) used as one of separation units is an apparatus for introducing an unknown mixed sample to a separation column to be adsorbed on a column surface, and feeding a mixture of plural solvents to the separation column while changing a mixing ratio of the solvents, thereby separating the sample into individual components based on a difference in reaction between each compound and the separation column. A combination of liquid chromatograph—mass spectrometer (LC/MS) is an apparatus for successively introducing the sample components separated by the LC to the mass spectrometer (MS) for detection of the components. When the sample components are successively introduced from the LC to the MS along with the solvents, each component is ionized by an ion source and produced compound ions are separated and detected depending on a mass-to-charge ratio (m/z). The detected result is accumulated for each retention time in the LC in the form of a chromatogram including the retention time and the mass spectrum.
The components in the mixed sample are represented as respective peaks in the chromatogram. By searching a mass spectrum database to find a mass spectrum having the same peaks, the structure of a compound represented by the peaks is identified. Also, the quantity of each component can be determined from a value of the peak area in the chromatogram.